A machine of this type with a device for regulation of the tension of the belt is described for example in patents AT 130902 and EP 0 459 894, to which reference will be made for further details.
The rotary electrical machine can be an electric motor, as in patent AT 13 902. As can be seen in FIG. 1, which is similar to that of patent AT 130902, this machine 1 comprises a device for regulation of the tension of the belt, comprising a regulation arm 10′ which pivots around a nose provided with a pivot integral with a front flange 2′ belonging to a housing of the machine, and supporting a roller 9′ for tensioning of the belt which penetrates into a pulley (with no reference) integral with the end (not shown) of a rotor shaft of the machine, which, as is known, is integral with a rotor. The housing, and thus the front flange 2′, is formed in a known manner in order to be secured on a fixed part. This flange 2′ constitutes a support flange for the device for regulation of the tension of the belt.
More specifically, the flange 2′ supports a support arm 7′ for a traction spring 8′ which is connected to the arm 10′ with the presence of a nut 12′ for regulation of the tension of the spring 8′. In this embodiment, the flange 2′ has a stop 3′ for receipt of a nose 5′ of an arm 6′, the upper end 7′ of which acts as a support for the spring 8′ exerting a force on the end 7′.
The rotary electrical machine can be an alternator, as described in patent EP 0 459 894, which also describes a rotary electrical machine provided with a pulley (not shown) for receipt of a belt, and with a device for regulation of the tension of the belt, comprising a tensioning roller, regulation arm which is mobile in rotation relative to a front end flange of the alternator designed to be secured on the engine block of a motor vehicle, and means for maintenance and/or regulation of the tension of the belt. According to one embodiment, the means for regulation of the tension of the belt consist of a spiral spring which is integral with the front flange and the regulation arm, with the said spring exerting a displacement force on the tensioning roller for an optimum tension of the belt. As a variant, the regulation means comprise a toothed sector which is provided on the regulation arm, and is designed to cooperate with a toothed sector with a complementary form integral with the front flange of the electrical machine. According to another embodiment, the toothed sectors consist of racks. The front flange comprises a square which is provided with holes so that it can be secured by means of securing means, such as screws, on the engine block of the motor vehicle. This flange also constitutes a flange for support of the device for regulation of the tension of the belt. The tensioning roller is fitted such as to rotate on the arm advantageously by means of a ball bearing which is interposed radially between the inner periphery of the roller and a pivot, which is a bolt in this embodiment, and is integral with the front flange, as described and shown for example in FIG. 2 of this patent EP 0 459 894.
In all cases, thanks to the device for regulation of the tension of the belt, optimum tension of the belt is obtained, sliding of the belt is prevented, and there is filtration of the vibrations which can detract from the satisfactory operation of the rotary electrical machine, in the knowledge that these vibrations can break the securing projections, such as ears or lugs or plates, which the housing with a front flange of an electrical machine has, in order to secure it on a fixed part, such as the engine block of a motor vehicle.
The belt can have a flat form with a trapezoidal cross-section, or it can consist of a poly-V (registered trademark) belt, with the transmission of movement between the flexible belt and the pulley taking place by adhesion according to one embodiment.
The pulley can be made of metal, such as steel for example, or aluminium which is anodised for example. As a variant, the pulley is made of plastic material reinforced by fibres and/or fillers in order to reduce the noises. This pulley comprises a groove which is complementary to the form of the belt, for receipt of the latter. When the pulley is made of metal, it can be covered locally with plastic material in particular at its groove.
The groove in the belt can comprise a groove with parallel flanks and a smooth base for receipt of a flat belt. As a variant, the groove in the pulley can have a trapezoidal form, in order to receive a belt with a trapezoidal cross-section, which transmits more torque than a flat belt. As a variant, the pulley can comprise a base provided with furrows for receipt of the teeth of a poly-V (registered trademark) belt, which belt is striated in the direction of the length. The lower part of the belt is in all cases designed to cooperate with the base of the groove in the pulley, whereas the upper part of the belt is designed to cooperate with the tensioning roller (see FIG. 1).
In a known manner, the belt is flexible, and comprises a body based on elastomer reinforced by fibres and a force armature consisting of cables such as polyester cables. This belt is known as a rubberised belt. The composition of the body based on elastomer, known as the base rubber, depends on the different belt manufacturers.
Thus, a belt with a trapezoidal cross-section comprises for example an upper part comprising a twill fabric, a force textile armature consisting for example of polyester cables, a base body made of elastomer belonging to the lower part of the belt, which body is reinforced by transverse fibres resistant to abrasion, and a rubber, for example polychloroprene, which is resistant to oils, and ensures static and dynamic adhesion to the textile armature. Advantageously, the inner part of the belt is provided with notches in order to increase the flexibility of the belt and limit the heating.
A poly-V belt differs from a trapezoidal belt in that its base body is provided with striations in the direction of the length, with teeth with a triangular cross-section belonging to the lower part of the belt. The furrows in the base of the groove in the pulley are designed to receive the teeth of the belt in a complementary manner.
In a known manner, poly-V belts are more advantageous than belts with a trapezoidal cross-section, since:
they are more flexible, which permits use on pulleys with a smaller diameter;
they permit optimum adhesion on the entire surface of the pulley, and homogenous distribution of the contact pressure between the belt and the pulley;
they make possible higher movement transmission ratios;
a single belt is sufficient for example, in order, from the pulley of the crankshaft of a thermal engine of a motor vehicle, to drive the motor vehicle alternator and another accessory of the motor vehicle, such as the fan or its air-conditioning compressor.
As a variant, the pulley comprises a groove with a base forming meshing for receipt of complementary notches contained on the base body made of elastomer of the belt with fabric and cable force textile armature. In this embodiment, the force is then transmitted by adhesion and meshing.
A conventional rotary electrical machine comprises a housing on which there is fitted firstly a stator and secondly, centrally by means of bearing means such as ball bearings with one or two rows of balls, a shaft of a rotary rotor. The shaft is integral with a rotor which rotates inside the stator. The pulley is fitted on the exterior of the housing and at one of the ends of the shaft, known as the front end, for example by screwing. The housing is designed to be secured on a fixed part, and comprises at least one front flange adjacent to the pulley, and a rear flange which is furthest away from the pulley. These flanges are known respectively as the front bearing and the rear bearing. The shaft passes through the bearings.
In the case of an electric motor, the stator is an inductor stator, and the rotor is an induced rotor. In the case of an alternator, in particular for a vehicle with a thermal engine, the stator is an induced stator and the rotor is an inductor rotor.
As is known, the rotor can be a claw rotor, a wound rotor with projecting poles, or a rotor with permanent magnets implanted radially and/or axially in the body of the rotor comprising a set of plates. The claw rotor or the projecting poles rotor can be provided with permanent magnets, in particular in order to increase the power of the rotary electrical machine.
In order to decrease the effects of Foucault currents, the stator can comprise a body in the form of a set of plates supporting a stator winding which extends on both sides of the stator body comprising windings with continuous wires or in the form of bars. The body of the stator has an axial length which is shorter than, or equal to, that of the rotor. The axis of the rotor shaft constitutes the axis of rotation of the electrical machine, and the axial axis of symmetry of the rotor and of the stator body constituting two coaxial parts. An air gap exists between the inner periphery of the stator body and the outer periphery of the rotor body.
The electrical machine can be of the polyphase type comprising at least three phases. A rectifier bridge or an inverter can be associated with the stator winding, in order in particular to transform the induced alternating current produced by the stator into direct current, in order to supply the consumers of the motor vehicle and/or to recharge the battery of the vehicle.
The front bearing is advantageously perforated for circulation of the air and cooling of the electrical machine.
As a reminder, reference will be made for example to document FR 2 739 734 which describes a rotary electrical machine in the form of an alternator shown in FIG. 2, which is a view in cross-section of a conventional alternator identical to FIG. 1 of document FR 2 739 734. A machine of this type can comprise a housing 1a, 1b which is designed to be secured on a fixed part, and comprises at least two flanges which are known respectively as the front bearing 1a and the rear bearing 1b, and are advantageously made of aluminium, in the knowledge that the front and rear correspond to an orientation from left to right in this FIG. 2.
These bearings 1a, 1b are assembled for example by means of tie rods, such as to retain between them on their outer periphery a stator 6 comprising a stator body in the form of a set of plates which supports a stator winding extending on both sides of the body of the stator, and passing through the latter. For this purpose, this body has in this embodiment recesses for the passage of the wires of a polyphase stator winding in the form of continuous conductive wire windings with a layer of electrical insulation such as enamel. The housing 1a, 1b is designed to be secured on a fixed part.
In this embodiment, the bearings 1a, 1b have a hollow form, and each have on their outer periphery a peripheral rim with a globally annular form designed to retain the body of the stator 6, in this case by means of a shoulder provided on their free end. These bearings 1a, 1b each have centrally a cylindrical receptacle for fitting of bearing means, in this case respectively a front ball bearing 7 and a rear ball bearing 8 receiving such as to rotate it a metal shaft 9 of a rotor, which supports integrally a rotor 20. The shaft 9 passes through the bearings 1a, 1b, which each have a sleeve for formation of the receptacle respectively of the bearing 7 and the bearing 8.
The outer ring of the ball bearing 7 is in close contact with the outer edge of the receptacle of the front bearing 1a, whereas an expansion ring is interposed radially between the outer edge of the receptacle of the rear flange 1b and the outer periphery of the outer ring of the ball bearing 8. The outer edge of the receptacles is constituted by the inner periphery of the sleeves.
The receptacles of the bearings 1a, 1b are perforated centrally for passage of a shaft 9, the outer periphery of which is in close contact with the inner periphery of the inner rings of the bearings 7, 8. The front ball bearing 7 has a larger diameter than that of the rear ball bearing 8.
In this FIG. 2, the shaft 9 has an axial axis of symmetry which is represented in FIG. 2, and the terms axial, radial and transverse will be used with reference to this axis which constitutes the axis of rotation of the alternator. The same applies in the other figures.
The rotor 20 is a claw rotor which in this embodiment comprises two magnet wheels 4, 5 and a central core which is implanted between the magnet wheels, and supports an excitation winding 21. The central core can be distinct from the magnet wheels, or it can be in two parts each of which is integral with one of the magnet wheels 4, 5. The magnet wheels 4, 5 and the central core are advantageously made of ferromagnetic material, and the same applies to the shaft 9 on which the wheels 4, 5 and the hub are secured, for example by means of knurled portions of the central shaft 9 which passes through the wheels 4, 5 and the hub.
These wheels 4, 5 each have a flange which supports on its outer periphery teeth with globally axial orientation, respectively 41, 51, which are imbricated in one another, whilst leaving between one another gaps such that the teeth of one of the magnet wheels face axially towards the flange of the other magnet wheel. An air gap exists between the outer periphery of the claw rotor 20, constituted by the outer periphery of the teeth 41, 51, and the inner periphery of the body of the stator 6 with an axial length which is smaller than, or equal to, the axial length of the rotor 20. In this embodiment, the teeth 41, 51 have leading 43, 53 and trailing 42, 52 edges, which are curved relative to the direction of rotation designated by the arrow F1, such as to give rise to circulation of the air according to the arrow F2 in all the gaps between the teeth 41, 51.
As a variant, in a conventional manner, the teeth 41, 51 are not curved, and have a globally trapezoidal form.
The front face of the wheel 4 has a front fan 10 secured on it, whereas the rear face of the wheel 5 has a rear fan 12 secured on it, such that the rotor 20 is flanked by two internal fans 10, 12, which are implanted in the housing 1. The fans 10, 12 have blades respectively 11, 13, and are perforated centrally for the passage of the shaft 9 of the rotor 20. The blades 11, 13 can be formed such as to form centrifugal fans. As a variant, the blades 11 of the front fan 10 can be formed in order to constitute a combined fan with radial and axial action. As a variant, it is possible to eliminate the front fan 10, with the flange and the peripheral teeth 41 of the wheel 4 constituting a fan.
The bearings 1a, 1b are perforated, and in this embodiment each have axial air inlets, respectively 15, 17, and radial air outlets, respectively 14, 16, such that the internal fans 10, 12 ensure circulation of the internal air in cooperation with the inlets 15, 17 and the outlets 14, 16, in order to ensure cooling of the components of the alternator, in particular of the winding 21, of the stator 6, and of the bearings 7, 8. The air outlets 14, 16 are mostly each arranged respectively in the annular peripheral rims with globally axial orientation of the bearings 1a, 1b. The air inlets 15, 17 are provided respectively in a front nose 18 which the front bearing 1a has, and in a base with transverse orientation of the rear bearing 1b. The receptacles with a cylindrical form of the bearings 7, 8 are provided centrally in the nose 18 of the bearing 1, and in the base of the bearing 1b, each having an aforementioned sleeve for accommodation of the bearings 7, 8. The nose of the bearing 1a is connected to the peripheral rim of the bearing 1a by a frusto-conical wall with slight inclination which constitutes the base of the bearing 1a. The inlets 15 are provided in the nose 18, whereas the outlets 14 with an oblong form are provided for reasons of withdrawal partly in the frusto-conical wall and partly in the peripheral rim of the bearing 1a, as can be seen in this FIG. 2.
On the front side, on the exterior of the housing 1a, 1b, the alternator comprises a pulley 3 which is made of metal or reinforced plastic material, adjacent to the front end of the front bearing 1a. 
The pulley 3, which for example is made of steel or aluminium, or as a variant of plastic material reinforced by fibres and/or fillers, comprises a groove 31, the base of which is provided with furrows for receipt in a complementary manner of the teeth of a poly-V belt, not represented for the sake of greater clarity. There are six teeth and furrows in this embodiment.
The pulley 3 is provided with a cavity (with no reference) with a transverse base, for receipt of a nut (with no reference), which is screwed onto the threaded front end of the rotor shaft 9, which for this purpose passes through a central opening which the base of the cavity in the pulley comprises. At the rear, this pulley 3 comprises a sleeve (with no reference) through which the shaft 9 passes, and which is in contact at the rear with the front end of the inner ring of the ball bearing 7. As a variant, the sleeve of the pulley is replaced by a ring. For further details on the fitting of the pulley 3 on the front nose 18, reference will be made to FIG. 3, which is a front view of the alternator in FIG. 2. It can be seen that a brace 33 in the form of a ring through which the shaft 9 passes is interposed axially between the rear end of the inner ring of the bearing 7 and the front end of the front magnet wheel 4 which is secured on the shaft 9, as well as the hub, for example, in a conventional manner, by means of a knurled portion 30 of the latter. Thus, the pulley 3 is integral in rotation and in translation with the shaft 9. It will be noted that the brace 33 is shorter axially than the inner ring of the bearing 7.
In this FIG. 3, the reference 31 designates the groove in the pulley, whereas the reference 36 designates the threaded part of the rotor shaft 9 which passes through the nose 18 of the front bearing provided with a sleeve 22, in which the outer ring of the bearing 7 is fitted. The outer ring of the bearing 7 is wedged axially between a retention part (with no reference) and a shoulder provided at the front of the sleeve 22 closed by a ring 32 interposed between the pulley 3 and the balls of the bearing 7, advantageously in a sealed manner. The ring 32, with an annular form, has the front end of the shaft passing through it, and constitutes a protective ring which prevents the introduction of water or dirt at the bearing 7. The retention part, with an annular form, is perforated centrally for passage of the brace, and has in its outer periphery holes, for example four of them, for the passage of units, in this case screws (with no reference) for securing on the sleeve 22 which is tapped for this purpose. The front bearing 1a thus has a nose 18 provided with a receptacle for fitting of a ball bearing 7, the inner ring of which is integral in rotation with a rotor shaft 9 which passes through the nose 18 of the front bearing 1a, in order to support in a fixed manner a pulley for receipt of a flexible movement transmission belt 3.
The rear magnet wheel 5 is integral with the shaft 9, also by means of a knurled portion of the latter. The rear end of the shaft 9 passes through the base of the rear bearing 1b, and has a smaller diameter than the front end of the shaft 9, which is mechanically subjected to greater stress because of the presence of the pulley 3 for receipt of the movement transmission belt. This is why the bearing 7 has a larger diameter than the bearing 8.
This shaft 9 has at its rear end two collector rings with no reference.
These collector rings belong to a connector which is added onto the rear end of the shaft 9, as described for example in document FR 2 710 199. This connector thus has a body made of electrically insulating material, such as plastic material, fitted onto the rear end of the shaft 9, and supporting the collector rings. At the front, this connector body has two arms, in each of which an electrically conductive tongue is embedded for electrical connection of one of the ends of the excitation winding 21 of the rotor 20 to the collector ring concerned, as can be seen better in FIGS. 10 and 11 of this document FR 2 710 199, also showing firstly the expansion ring interposed radially between the outer edge of the receptacle with a sleeve of the rear bearing 1b and the outer periphery of the outer ring of the rear bearing 8, and secondly, the knurled portion of the shaft 9 for connection of the rear magnet wheel 5 of the rotor 20 to the shaft 9, in the knowledge that the rear fan 12 in this case has blades with a radial height greater than that of the front fan 10, which is less powerful.
The base of the rear bearing 1b supports at the rear (on the side opposite the rotor 20) a brush-holder (with no reference) which belongs in a known manner to a tension-regulating brush-holder assembly which the alternator has.
The brush-holder has two brushes which are each designed to come into contact with one of the collector rings of the connector, for the electrical supply of the winding 21 of the rotor.
The lower part of this FIG. 2 shows the connection of one of the ends of the winding of the stator to one of the electrical conductors of a connector (with no reference), which in this example belongs to a bridge for rectification of alternating current into direct current which is supported by the base of the bearing 1b on the rear side of the latter. This bridge comprises negative diodes for example which are fitted into the base of the rear bearing 1b, constituting a heat dissipater, and positive diodes which are fitted in an electrically conductive positive heat dissipater which supports a terminal for connection by means of a cable to the positive terminal of the battery of the motor vehicle. The positive dissipater is insulated electrically by the rear bearing. The diodes can be fitted for example head to tail, as in document FR 2 734 425, to which reference will be made for further details. This document also shows the brush-holder tension regulator assembly. As a variant, the tails of the diodes are oriented axially in the same direction.
The number of pairs of diodes depends on the applications, in particular on the number of phases which the alternator comprises. For example, for a three-phase machine, at least three pairs of diodes are provided. In a known manner, the number of teeth 41, 51 which each wheel 4, 5 has varies between six and eight. The number of notches in the body of the stator 6 depends on the number of phases of the alternator. Thus, for wheels 4, 5 which each have six teeth, for a three-phase alternator 36 notches are provided in the body of the stator 6. For wheels 4, 5 which each have seven teeth and an alternator with seven phases, 98 notches are provided in the body of the stator 6. For wheels 4, 5 which each have six teeth and an alternator with seven phases, 84 notches are provided in the body of the stator 6.
The number of phases of the alternator can be 3, 5, 6 or 7 phases, with two windings being able to be provided per phase. The phases can be fitted in the form of a star and/or a triangle, with the connector of the bridge being arranged accordingly.
This FIG. 2 shows that the assembly of the electronic components (diodes, voltage regulator) are supported by the base of the electrically conductive rear bearing 1b, like the front bearing 1a. This bearing 1b comprises a projection (with no reference) for securing on a fixed part, for example in the form of a lug or ear which is perforated for the passage of means, such as a screw or rear bearing 1b, for securing on the engine block of the motor vehicle. This bearing 1b is thus connected electrically to the earth, and constitutes a negative heat dissipater. The same applies to the front bearing 1a, which has two projections (with no reference) for securing on a fixed part, for example in the form of lugs or ears, which are perforated for the passage of means, such as screws, for securing of the rear bearing on the engine block of the vehicle. The housing 1 of the alternator is thus secured at three points on the engine block. As a variant, the fixed projections consist of at least one plate with orientation which is tangential relative to the peripheral rim of one of the bearings 1a, 1b with which it is integral. This plate comprises at least one hole, and as a variant two holes, for passage of means for securing on the engine block of the vehicle. Two diametrically opposite plates can be provided on the front bearing 1a. It will be appreciated that the number of securing points depends on the applications.
A perforated protective cover 2, which for example is made of reinforced plastic material or sheet metal, covers the brush-holder tension regulator assembly and the rectifier bridge. This cover 2 is integral with the rear bearing 1b, whilst having a hollow form. Openings (with no reference) are provided in the base of the cover and in the peripheral skirt which the cover 2 has on its outer periphery for the circulation of the air inside the machine by means of the rear fan 12, which thus cools the integrated electronics of the alternator, and for this reason is more powerful than the fan 10.
In a known manner, the alternator is implanted in the vicinity of the front face of the engine block of the vehicle and the movement transmission belt intervenes between a drive pulley which is integral with the crankshaft, and the pulley 3 which constitutes a driven pulley. The pulley of the crankshaft is implanted at the front face of the engine block of the vehicle. The belt can also be used to drive another accessory of the vehicle, such as the pulley of the air-conditioning compressor or the water pump pulley, which accessory is implanted in a known manner in the vicinity of the front face of the vehicle.
When the thermal engine of the vehicle is running after being started by means of a starter, and the excitation winding 21 of the rotor 20 is supplied electrically via the brush-holder tension regulator assembly, the rotor 20 is magnetised, and the teeth 41, 51 constitute North and South poles, and create an induced magnetic flux in the stator 6. An alternating current then circulates in the winding of the stator 6. This alternating current is then rectified in the bridge in order to produce a direct current, so as to supply the consumers of the vehicle with power and/or recharge the battery of the vehicle.
As a variant, the current rectifier bridge is replaced by an inverter, comprising for example transistors of the MOSFET type, replacing the diodes as described for example in document FR 2 745 444. Means for monitoring the rotation of the rotor, such as, firstly, Hall-effect sensors supported by a sensor-holder opposite a magnetic target supported for example by the rear fan 12 or the magnet wheel 5, associated with a magnetic target, or secondly a resolver, are associated with this inverter. This therefore creates a reversible alternator known as an alternator-starter, which makes it possible in particular to replace the starter in order to start the thermal engine, with the alternator then operating in electric motor mode to drive the pulley 3, which then becomes a drive pulley driving the pulley of the crankshaft. The electronic components of this inverter can then be supported by a casing which is distinct from the machine, or can be integrated in the machine whilst being fitted above the rear bearing 1b for example, on a mezzanine which is integral with the rear bearing 1b, and belongs to the housing. In addition to its function as a starter and its function of starting and stopping the thermal engine (known as the stop-start function), the alternator-starter can carry out other functions depending on its power, i.e. in particular a function of recuperative braking, a function of charging an ultra-capacitor, and a function of preventing stalling of the thermal engine of the motor vehicle.
A problem then occurs when it is wished to equip this rotary electrical machine with a device for regulation of the tension of the belt, since in the aforementioned patents the front bearing has an additional function of supporting this regulation device.
In patent AT 130902, the front bearing is not designed to permit circulation of the air inside the rotary electrical machine.
In patent EP 0 459 894, the housing has a complicated form, taking into account the fitting (not shown) to be carried out of the pulley.
Without changing the size of the rotor and the stator, it is conceivable to make the flange for support of the belt tension regulation device distinct from the front bearing, and to secure this support flange on the housing of the electrical machine. This leads to an increase in the cantilever of the pulley, and thus in particular to an increase in the size of the rear bearing, which has an effect on the mechanical and/or electronic environment of the rotary electrical machine, since the size of the rear bearing 8 should not be increased in order to avoid any mechanical interference, in particular with the rear fan 12, or with the sensor-holders, or with the resolver.
Modification of the protective cover should also be avoided, and, when the rotary electrical machine is provided with integrated electronics, so should modification of the interface with the integrated electronics of the machine.